The focus of this laboratory has been the MHC class I molecule, classically considered a molecular heterodimer consisting of a 46 kd polymorphic heavy chain, exemplified by the murine H-2K, D, and L molecules (analogous to the human HLA-A, -B, and -C molecules), that is non-covalently assembled with the 12 kd monomorphic light chain, beta2-microglobulin. Our objectives under this project title have been to evaluate: 1) the influence of beta2-microglobulin and serum proteases on functional and biochemical binding of MHC class I molecules to antigenic peptides; 2) the expression and function of domain and sub-domain fragments of class I molecules generated by recombinant DNA methods, and expressed in tissue culture cells; 3) the function of soluble MHC class I molecules in a transgenic mouse model system; and 4) the production and function of single chain MHC class I molecules.